Process of purifying water.



UNITED STATES PATENT oEEIoE.

CHARLES ARTHUR BROWN, OF LORAIN', OHIO, ASSIGNOR TO AMERICAN STEEL ANDWIRE COMPANY, A CORPORATION OF NEW JERSEY.

Specification of Letters Patent.

Patented July 10, 1906.

Application filed September 5, 1905. Serial No. 276,961.

To all whom it may concern:

Be it lmown that 1, CHARLES ARTHUR BROWN, of Lorain, in the county ofLorain, State of Ohio, have invented a new and useful Process ofPurifying Water, of which the following is a full, clear, and exactdescription.

When a water containing sediment or mud is allowed to stand at rest fora sufficient length of time, the larger portion of the suspended matteris removed from the water by sedimentation. If the proper chemicals beadded to a water in this condition, the particles of suspended matterare gathered together in larger masses, the precipitation is more rapidand complete, and the resulting purification is much more rapid andsatisfactory. When chemicals are employed to bring about this result,the chemicals so used are termed coagulants. After a water has beenproperly coagulated it may be passed through a filter plant at a muchhigher rate of speed and a better purification effected than if the samewater were to be passed through the same system and no chemicalsemployed. The chemicals which are used for this purpose are in theprocess converted into insoluble compounds and soluble comounds, thesoluble compounds being harmess and inoffensive, the insoluble compoundscausing the coagulation to occur and being removed with the impuritieswhich the water contains. Various chemicals have been employed in thepast for the purpose of producing this coagulation. Among suchsubstances may be mentioned the difierent salts of aluminium, iron,lime, and soda. In the process of sedimentation or sedimentation .andfiltration, or by filtration where no sedimentation is employed, a largepercentage of the bacteria, which all natural waters carry to a greateror less extent, is removed from the water either by the processes ofsedimentation, filtration, or the combined action of the two. Thisremoval is largely of a mechanical nature. Various attempts have beenmade to kill the bacteria which these natural waters carry. Variouschemicals and processes have been used for this purpose. Ithas beenfound ossible to practically sterilize a water by t e use of some ofthese methods; but in the majority of instances such treatment did notaffect the 7, physical character of the water, and it remainedpractically unimproved in that respect. If amuddy water containingbacteria were to be subjected'to the process of sterilization, the waterwould not be improved in physical appearance to any great extent, and tobring about such improvement some process of sedimentation or filtrationor a combination of these processes would have to be resorted to. If awater be passed through a sand-bed at a sufficiently low rate of flowunder proper conditions, the same may be purified to a very greatextent, as is exemplified in the slow sand method of filtration. Usuallyin this process no chemicals are employed. If chemicals are employed tocoagulat-e the water, a much higher rate of filtration is permissibleand equally as thorough and complete purification may be efiected. Inthe process of purifying water by sedimentation or filtration or acombination of these two methods where chemicals are employed none ofthe methods of the past prior to my invention have effected anypractical sterilization of the water so purified by chemical means.

The danger of using an unpurified water for domestic purposes is veryargely due to the fact that most-of our natural waters are contaminatedto a greater or less extent by sewage. If all traces of sewagecontamination can be removed, such a water will be safe for humanconsumption evenif the physical appearance of the same may beobjectionable. Sewage contamination is indicated by the presence ofvarious species of bacteria. Among these may be mentioned the Bacilluscoll-communisand the Bacillus typhosus. So far as We now know theBacillus colt-communes is not dangerous; but it is normally present inall sewage, and therefore serves as an indication of sewagecontamination. As a general statement it may be said that 'anysewage-contaminated water will at some time or other contain thebacillus of typhoid fever. The purification of a public water-supply iseffected to bring about the removal of these two species of bacteria andalso to clarify the water, so as to render same suitable for use. In thepresent state of our knowledge it is thou ht that if a water be freefrom Bacillus col-commuwis there will be no sewage contamination andthat therefore the water will be safe for human consumption. In allprocesses of sedimentation, filtration, or sterilization the end soughthas been the clarification of the water and the removal of theseparticular forms and the rendering of the water so purified'safe andsuitable for human usage. By the use of coagulants and sedimentation orfiltration or a combination of these two processes it has been foundpossible to remove large percentages of the mud and bacteria which thenatural water carries. It has been known for some time that sulfate ofcopper if applied to a water-supply in sufiicient quantities would bringabout a practical sterilization of such water-supply by effecting thedeath of the two species of bacteria above spoken of; but the amountsrequired were so large as to make the process of little public utility.

I have discovered that by combining sulfate of copper with sulfate ofiron in small proportions as a combined coagulant and germiclde equallyas good germicidal results can be obtained as if copper sulfate alonewere employed in larger quantities, while the coagulating value of thesulfate of iron is not in any way interfered with, and these results canbe obtained at a cost which renders the process a commercial andpractical one. A test of this process was made at the city of Lorain,Ohio, in a mechanical filter plant having a daily capacity of threemillion gallons per twenty-four hours at normal rate of operation. Thisplant furnishes a purified water for use of the entire city of Lorain.Two tons of copper-iron sulfate were used in this test. Varying amountsof this mixture were dissolved in the chemical-tanks of said mechanicalfilter plant and injected into the water on its way to thesettling-basins composing a part of this plant. About one and one-halfgrains of this substance were used for each gallon of water treated, anda smaller amount of caustic lime was also injected into each gallon ofthe water so treated. A perfect coagulation. resulted which separatedfrom the water artly in the sedimentationbasins and part y in and on thesand-beds cpmposing a part of said mechanical filter ant. that all ofthe Bacillus colt-commands was either killed or removed from the water.As this is considered the most reliable test for the presence of sewa e,it was judged that its absence from the ter-water indicated the entireabsence of sewage contamination. It may be stated that this bacillus isordinarily present in the untreated water entering the filter plant atthis point almost universally and was so present at the time these testswere conducted. A larger quantity of sulfate of iron containing coppersulfate was then manufactured and shipped to Anderson, Indiana, where anew filter plant was about read to be started in service, and a'test wascon ucted there in which the same results were obtained, the filteredwater being free It was found as a. result of this test' from any tracesof sewage contamination,

save on occasions where some error in the process would lead to theimperfect operation of the chemicals. A later test was conducted atMarietta, Ohio, on another filter lant, and in this last test completeremova and destruction of the sewage pollution resulted. From thesetrials of the process it has been proven that this combination ofsulfates of 1IOI1 and copper in connection with the use of caustic limewhen used in plants of this description, embodying the principles ofsedimentation, filtration, or a combination of these two, is capable ofproducing a water free from suspended matters and sewage contamination,and thereforea safe and pure water for human consumption.

The process is new in employing in combination with sedimentation orfiltration or a combination of the two a compound which acts as agermicide anda compound which acts as a coagulant whether added togetheror at different times, and therefore, broadly considered, othercoagulants than sulfate of iron, such as alum, may be employed. It isalso new employing a mixture of the sulifate of iron and copperpreferably with caustic lime which is applied in the form of milk oflime, lime-water, or dry hydrated lime. The caustic lime added in smallproportion, either simultaneously with the sulfate or at another time,removes practically all of the iron and copper from the water bysedimentation or by sedimentation and filtration. All of the chemicalsare preferably added in the sedimentation-tanks or just previous toreaching the sedimentation-tanks. The proportion .of sulfate of copperem loyed will vary according to the condition 0 the-water.

Ordinarily about one part of sulfate of co per to ninety-nine parts ofsulfate ofiron Wlll sufiice, the mixture being used, preferably, in theproportion of 1.5 grains per gallon of water; but the proportions may bevaried, and

as much as ten per cent. or as little as .5 per cent. ofsulfate ofcopper or less in the sulfate mixture may be used.

In the practice of my new process as above described the sulfate ofcopper or other equivalent compound is decomposed and the copper isprecipitated in the form of a carbonate or hydrate or a mixture ofthese,

forming a germicidal layer on the sand-bed through which all of thewater is filtered.

I claim 1 1. The herein-described method 0 mify ing water, whichconsists in treating t e water with a coagulant compound in the presenceof a relatively smaller amount of a connpound which is decomposed toform a germicidal' reci itate, and filteringthe water through sucprecipitate.

2. The herein-described method of puritying water, which consists intreating t e'water with a coagulant compound in the pres;-

l ence of sulfate of copper, the latter being ing'water, which consistsin treating the wa-.

ter witha coagulant compound in the'pres ence of sulfate of copper, andfiltering. 4. 'The method herein described of purifying water, whichconsists in treatin the water with sulfate of iron and sulfate 0 copper.

5. The'method'herein described of purifying Water, which'consists intreating the water with sulfate of iron and sulfate of copper, andfiltering.

6. The method herein described of purifying water, which consists oftreating the water with sulfate of iron and sulfate of copper, andcaustic lime.

7 The method herein described of purifying water, which consists oftreatin the water with sulfate of iron and sulfate 0 copper,

and caustic lime, and filtering.

8. The method herein described of urifying water, which consists oftreating t e water with sulfate of iron and a smaller pro-. portion ofsulfate of co per.'-

9. The method herein described of purifying water which consists oftreating the water with sulfate of iron and a smaller proportion ofsulfate of. copper, and filtering.

. 10. The herein-described method ofpurifying water, which consists intreatin water with a soluble sulfate of sesquioxid orming substance anda germicide compound which is decomposed and preci itated to form asgermicidal la er, and through such it. er, the amountof the germicidecompound eing less than the amount of the coagulant substance.

11. The method herein described of purifying Water, which consistsin'treating the water with a soluble sulfate'of a sesquioxid formingsubstance, and sulfate of co per.

12. The method herein describe of purifying water, which consists intreating the water with a soluble sulfate of a sesquloxid formingsubstance, and sulfate of copper, and filtering.

In testimony whereof I have hereunto set my handi p C. ARTHUR BROWN.

Witnesses:

h C. P. BYRNES,

GEO. B. BLEMING.

tering the water

